How can a biomass pyramid be inverted?

A biomass pyramid can be inverted if the lowest level of the pyramid (the autotrophs) is small in weight but very fast reproducing. Thus the herbivores above keep the size small, but this small population is swiftly able to reproduce, at a level sufficient to mitigate losses from predation. For example, many ocean biomass pyramids are inverted. read more

Ecological pyramids show the relative amounts of various parameters (such as number of organisms, energy, and biomass) across trophic levels. Ecological pyramids can also be called trophic pyramids or energy pyramids. Pyramids of numbers can be either upright or inverted, depending on the ecosystem. read more

It means its not a pyramid shape and this can happen because the consumers of the producer can be less. read more